Issue Eur. Phys. J. D Volume 38, Number 3, June 2006 Page(s) 471 - 479 Section Atomic Physics DOI 10.1140/epjd/e2006-00061-y Published online 21 March 2006

Eur. Phys. J. D 38, 471-479 (2006)
DOI: 10.1140/epjd/e2006-00061-y

Helium atom in presence of DC and AC electric fields

I.A. Ivanov and A.S. Kheifets

Research School of Physical Sciences and Engineering, The Australian National University, Canberra ACT 0200, Australia

igor.ivanov@anu.edu.au

(Received 29 November 2005 / Published online 21 March 2006)

Abstract
We investigate the effect of a static electric field on photoionization of the He atom in the ground 1S and low-lying 2S and 2P excited states. The field-affected ionization potential and photoionization cross-section are determined from the complex eigenvalues of the time-dependent Schrödinger equation solved by the complex rotation method in the Floquet ansatz. Accuracy of the method is enhanced by the use of the Hylleraas basis set. For the ground state of helium, we find that the total photoionization cross-section remains constant or decreases as a function of the DC field strength until this field reaches a certain critical value. For the low-lying excited states, effect of the static field is similar to the ordinary DC Stark effect.

PACS
32.80.-t - Photon interactions with atoms.
32.80.Fb - Photoionization of atoms and ions.
42.50.Hz - Strong-field excitation of optical transitions in quantum systems; multiphoton processes; dynamic Stark shift .

© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2006

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